Monday and Tuesday are usually quietest, with Wednesday and Thursday not much busier. Friday tends to be fairly busy, but Saturday is easily the busiest. The public holidays always draw a big crowd, too, and, while this is not usually a problem in the main part of the Center (apart from at main meal-times), it can cause some long queues on the bus tours (notably if you get off at one of the two stops and then want to catch another bus back).